Are associated with better overall survival and JAK2, CALR, and MPL tripe-negative patients show inferior survival in PMF.1

Importance of CALR Testing in MPN Patients

The most frequent genetic mutation in the Philadelphia chromosome-negativemyeloproliferative neoplasms (ET and PMF) is the JAK2V617F mutation, which is present in approximately 50% to 60% of these patients. The JAK2V617F serves as a confirmatory molecular marker of these diseases.

Mutations in the MPL gene are found in an additional 4% to 10% of ET and PMF cases. Somatic mutations (insertions and/or deletions) in exon 9 of the CALR gene were recently discovered to be the second most frequent somatic mutation (after JAK2V617F) in ET and PMF patients and appears to be mutually exclusive of the JAK2 and MPL mutations.2,.3 It has a reported frequency of approximately 50% to 90% in JAK2 and MPL-wild type (WT) ET and PMF, and importantly is not found in polycythemia vera (PV) patients.2-5

Therefore, a CALR mutation serves as an additional important diagnostic molecular marker in ET and PMF. CALR mutation status also has an important role in prognosis. For example, in PMF, a CALR mutation carries favorable survival impact and a triple-negative mutation status (JAK2, MPL and CALR-negative) has been identified as a high-risk molecular signature. CALR impact on survival in ET patient is uncertain, however, it is associated with lower risk of thrombosis in comparison to JAK2 and MPL mutations. 2,4,5

Andy Tofilon

Andy Tofilon is a Marketing Segment Manager at Mayo Medical Laboratories. He leads strategies for corporate communications, public relations, and new media innovations. Andy has worked at Mayo Clinic since 2003. Outside of work, Andy can be found running, hiking, snapping photos, and most importantly, spending time with his family.